World health officials are offering hope that the ebbing of the omicron wave could give way to a new, more manageable phase of the COVID-19 pandemic, even as they warn of difficult weeks ahead and the possibility of another, more dangerous variant arising - as reports emerged of a new version of the variant in some countries.

In the U.S., cases have crested and are dropping rapidly, following a pattern seen in Britain and South Africa, with researchers projecting a period of low spread in many countries by the end of March. Though U.S. deaths — now at 2,000 each day — are still rising, new hospital admissions have started to fall, and a drop in deaths is expected to follow.

The encouraging trends after two years of coronavirus misery have brought a noticeably hopeful tone from health experts. Rosy predictions have crumbled before, but this time they are backed by what could be called omicron’s silver lining: The highly contagious variant will leave behind extremely high levels of immunity.

On Sunday, Dr. Anthony Fauci talked on ABC “This Week” about a “best-case scenario” where COVID-19 would fall to manageable levels so the United States could get “back to a degree of normality.”

And on Monday, the World Health Organization issued a statement anticipating an end to the “emergency phase” of the pandemic this year and saying that the omicron variant “offers plausible hope for stabilization and normalization.”

Both Fauci and the WHO’s Europe regional director, Dr. Hans Kluge, cautioned that new variants are likely to emerge, but with vaccination, new drug therapies and — during surges — testing and masks, the world could reach a less disruptive level of disease in which the virus is, as Fauci put it, “essentially integrated into the general respiratory infections that we have learned to live with.”

In the U.S., new cases are averaging a still extraordinarily high 680,000 a day, down from an all-time peak of over 800,000 a little more than a week ago.

The places in the U.S. where omicron struck first are seeing the sharpest declines. New cases in the Northeast are nose-diving, while other states — Arizona, Texas, Oregon, Kansas and North Dakota among them — are still waiting for relief.

Falling, too, are new U.S. hospital admissions of patients with confirmed COVID-19. They are averaging nearly 20,000 per day, down about 7% from the previous week, according to the Centers for Disease Control and Prevention.

Those numbers include patients who went to the hospital for other reasons and tested positive. But even after accounting for these incidental infections, the trend is hopeful.

One influential model projects that nearly all nations will be past the omicron wave by mid-March, including China and other countries with “zero COVID” policies. The wave will leave behind high levels of immunity — both from infection and vaccination — that could lead to low levels of transmission for many weeks or months.

“What do we end up with at the end of this?” said Dr. Christopher Murray of the University of Washington, who developed the closely watched Institute for Health Metrics and Evaluation model. “We end up with the highest levels of global immunity that we’ve seen in the pandemic.”

The model estimates that 57% of the world’s population already has been infected with the virus at least once.

Another research group, which combines several models and shares the projections with the White House, predicts a strong decline in U.S. infections by April, unless a new variant emerges that can sidestep the growing levels of immunity.

“It would be dangerous to forget that possibility, as it has caught us before,” said Katriona Shea of Pennsylvania State University, a leader of the team that pulls together the models.

She noted, too, that the projections show 16,000 to 98,000 more Americans dying before the omicron wave is through. The U.S. death toll stands at close to 870,000.

“Even if we project a more optimistic future, right now we still have a lot of COVID spreading, a lot of strain in our hospital systems, and our deaths have not yet peaked,” said Lauren Ancel Meyers, director of the University of Texas COVID-19 Modeling Consortium.

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“There’s still a lot of pain before omicron has run its course,” she said, but added: “It’s very plausible that omicron will be a turning point in terms of our relationship with this virus.”

New version not a cause for alarm

A new version of the highly contagious omicron variant been spreading in parts of Asia and Europe, with the WHO recommending Monday that officials begin investigating its characteristics to determine whether it poses new challenges for pandemic-weary nations.

Known as BA. 2, the new version of the virus is a descendant of the omicron variant. Virologists are referring to the original omicron variant as BA. 1.

"The BA. 2 descendant lineage, which differs from BA. 1 in some of the mutations, including in the spike protein, is increasing in many countries," the WHO wrote on its website. "Investigations into the characteristics of BA. 2, including immune escape properties and virulence, should be prioritized independently (and comparatively) to BA. 1."

Viruses mutate constantly, mostly in harmless ways. There is no current evidence that BA. 2 is more virulent, spreads faster or escapes immunity better than BA. 1.

BA. 2 has been detected in India, Denmark and Britain, among other countries, according to health officials and media reports abroad. In Europe, it appears the most widespread in Denmark, but that may be because the Scandinavian nation has a robust program of sequencing the virus's genome.

At least three cases have been found in the United States at Houston Methodist Hospital in Texas, which also is studying the genetic makeup of virus samples from its patients.

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Kristen Nordlund, a spokeswoman for the US Centers for Disease Control and Prevention said, "Although the BA.2 lineage has recently increased in proportion in some countries, it remains a very low proportion of circulating viruses in the United States and globally. Currently, there are insufficient data to determine whether the BA.2 lineage is more transmissible or has a fitness advantage over the BA.1 lineage. CDC continues to monitor variants that are circulating both domestically and internationally."